Minimally invasive medical techniques are aimed at reducing the amount of extraneous tissue which is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. Millions of surgeries are performed each year in the United States. Many of these surgeries can potentially be performed in a minimally invasive manner. However, only a relatively small number of surgeries currently use these techniques due to limitations in minimally invasive surgical instruments and techniques and the additional surgical training required to master them.
Advances in minimally invasive surgical technology could dramatically increase the number of surgeries performed in a minimally invasive manner. The average length of a hospital stay for a standard surgery is significantly longer than the average length for the equivalent surgery performed in a minimally invasive surgical manner. Thus, the complete adoption of minimally invasive techniques could save millions of hospital days, and consequently millions of dollars annually in hospital residency costs alone. Patient recovery times, patient discomfort, surgical side effects, and time away from work are also reduced with minimally invasive surgery.
The most common form of minimally invasive surgery is endoscopy. Probably the most common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In standard laparoscopic surgery, a patient""s abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately xc2xd inch) incisions to provide entry ports for laparoscopic surgical instruments.
The laparoscopic surgical instruments generally include a laparoscope for viewing the surgical field, and working tools defining end effectors. Typical surgical end effectors include clamps, graspers, scissors, staplers, or needle holders, for example. The working tools are similar to those used in conventional (open) surgery, except that the working end or end effector of each tool is separated from its handle by, e.g., an approximately 12-inch long, extension tube.
To perform surgical procedures, the surgeon passes these working tools or instruments through the cannula sleeves to a required internal surgical site and manipulates them from outside the abdomen by sliding them in and out through the cannula sleeves, rotating them in the cannula sleeves, levering (i.e., pivoting) the instruments against the abdominal wall and actuating end effectors on the distal ends of the instruments from outside the abdomen. The instruments pivot around centers defined by the incisions which extend through muscles of the abdominal wall. The surgeon monitors the procedure by means of a television monitor which displays an image of the surgical site via a laparoscopic camera. The laparoscopic camera is also introduced through the abdominal wall and into the surgical site. Similar endoscopic techniques are employed in, e.g., arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy and the like.
There are many disadvantages relating to current minimally invasive surgical (MIS) technology. For example, existing MIS instruments deny the surgeon the flexibility of tool placement found in open surgery. Most current laparoscopic tools have rigid shafts and difficulty is experienced in approaching the surgical site through the small incision. Additionally, the length and construction of many surgical instruments reduces the surgeon""s ability to feel forces exerted by tissues and organs on the end effector of the associated tool. The lack of dexterity and sensitivity of surgical tools is a major impediment to the expansion of minimally invasive surgery.
Minimally invasive telesurgical systems for use in surgery are being developed to increase a surgeon""s dexterity as well as to allow a surgeon to operate on a patient from a remote location. Telesurgery is a general term for surgical systems where the surgeon uses some form of remote control, e.g., a servomechanism, or the like, to manipulate surgical instrument movements rather than directly holding and moving the instruments by hand. In such a telesurgery system, the surgeon is provided with an image of the surgical site at the remote location. While viewing typically a three-dimensional image of the surgical site on a suitable viewer or display, the surgeon performs the surgical procedures on the patient by manipulating master control devices, at the remote location, which control the motion of servomechanically operated instruments.
The servomechanism used for telesurgery will often accept input from two master controllers (one for each of the surgeon""s hands), and may include two robotic arms. Operative communication between each master control and an associated arm and instrument assembly is achieved through a control system. The control system includes at least one processor which relays input commands from a master controller to an associated arm and instrument assembly and from the arm and instrument assembly to the associated master controller in the case of, e.g., force feedback.
It would be advantageous if the control system establishes a relationship between master control and associated end effector as viewed in the image, in which relationship the orientation and position of the end effector as displayed to the surgeon in the image follows and corresponds with the orientation and position of the surgeon""s hand when manipulating the associated master controls. Thus, it would be advantageous if end effector orientation and position is mapped onto surgeon hand orientation and position. In such a case control of end effector movement would be performed in a more intuitive manner than in the case where end effector movement as displayed in the image were not mapped onto surgeon hand movement.
It would further be advantageous if the position of the image capturing device could be changed during the course of a surgical procedure so as to enable the surgeon to view the surgical site from another position. It will be appreciated that, should the image capturing device position change, the orientation and position of the end effectors in the viewed image could also change. It would further be advantageous if the relationship in which end effector movement is mapped onto hand movement could again be established after such an image capturing device positional change.
It is an object of the invention to provide a method and control system which permits the mapping of end effector movement onto hand movement to be established and/or reestablished after having been interrupted, for example, by an image capturing device positional change.
It is to be appreciated that although the method and control system of the invention is described with reference to a minimally invasive surgical apparatus in this specification, the application of the invention is not to be limited to this application only, but can be used in any type of apparatus where an input is entered at one location and a corresponding movement is required at a remote location and in which it is required, or merely beneficial, to realign or re-map slave orientational and/or positional movement onto master input movements after interruption.
In accordance with one aspect of the invention, there is provided a method of establishing or reestablishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including causing the end effector to remain stationary; determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer; determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which orientation the desired orientational relationship between the hand-held part of the master control and the end effector would be established or reestablished; and causing the hand-held part of the master control to be moved into the desired corresponding orientation.
The method may further include determining a current position of the end effector relative to the viewing end of the image capturing device operatively associated with the viewer; and determining a desired corresponding position of the hand-held part of the master control relative to the viewer at which position a desired positional relationship between the hand-held part of the master control and the end effector would be established or reestablished; and causing the hand-held part of the master control to be moved into the desired corresponding position.
According to another aspect of the invention, there is provided a surgical control system arranged to cause a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave, as viewed in a displayed image on a viewer, to be established or reestablished when operative control between the master control and the slave has been interrupted, the control system including processing means arranged to cause the end effector to remain stationary; processing means arranged to compute a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer; and to compute a desired corresponding orientation of the hand-held part of the master control at which orientation the desired orientational relationship between the hand-held part of the master control and the end effector would be established or reestablished; and an actuator arranged to cause the hand-held part of the master control to be moved into the desired orientation.
The surgical control system may further include processing means arranged to compute a current position of the end effector relative to the viewing end of the image capturing device operatively associated with the viewer; and to compute a desired corresponding position of the hand-held part of the master control at which position the desired positional relationship between the hand-held part of the master control and the end effector would be established or reestablished; and an actuator arranged to cause the hand-held part of the master control to be moved into the desired position.